JP2022023871A - Thermal power plant and waste heat recovery method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal power generation plant and an exhaust heat recovery method capable of further improving efficiency by using exhaust heat.

SOLUTION: The thermal power generation plant includes: a circulation type boiler system 2B that has a steam turbine 10 driven by steam, a condenser 11 that introduces exhaust steam from the steam turbine 10 and condenses the exhaust steam to be a condensed fluid, a circulation type boiler 13 evaporating the condensed fluid from the condenser 11 and introducing it to the steam turbine 10, a blow pipe 14 discharging a part of the condensed fluid from the circulation type boiler 13, a discharge fluid EW that is the condensed fluid from the blow pipe, and a heat exchanger 50 exchanging heat with a fuel F to make the fuel F recover heat; and a gas turbine 24 that introduces exhaust EG to the circulation type boiler 13, exchanges heat between the exhaust EG and the circulation type boiler 13, and burns the fuel after the heat recovery by the heat exchanger 50.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a thermal power plant and a waste heat recovery method.

For example, in a thermal power plant, a gas turbine combined cycle power plant that recovers the exhaust heat of a gas turbine and drives a steam turbine by the exhaust heat is used. In such a power plant, a circulating boiler is generally used. In addition to thermal power plants, circulating boilers are also used in coal-fired conventional power plants and the like.

In the circulation type boiler, the upper limit of the impurity concentration of the drum water is set by the standard or operation, and if the impurity concentration exceeds this upper limit, or if the impurity concentration is to be kept low, , It is necessary to drain the drum water out of the system continuously or periodically. Drum water has high enthalpy because it is high temperature and high pressure water. Therefore, when it is discharged, energy loss occurs, for example, a decrease in power generation efficiency with respect to the unit fuel, and a production cost of make-up water for replenishing the discharged water is incurred. Furthermore, since the discharge of high-temperature boiler water as it is may adversely affect the external equipment at the discharge position, it is necessary to install equipment for reducing the temperature of the boiler water and wastewater treatment equipment.

Here, in the nuclear power plant described in Patent Document 1, water is converted into steam by a steam generator using the heat generated in the nuclear reactor, and the steam is used to drive a steam turbine to operate a generator. In this plant, the exhaust steam that worked in the steam turbine is sent to the condenser, cooled by seawater, etc., and then returned to the steam generator via the condenser system that connects the condenser and the steam generator. There is. At this time, in order to prevent impurities from accumulating and concentrating in the steam generator, a part of the water in the steam generator is blown down (discharged) from the steam generator, and the blown down water is discharged into the condensate system. Returning to. Then, the heat of the water blown down from the steam generator is recovered by exchanging heat between the water blown down from the steam generator and the water of the condensate system using a heat exchanger.

Japanese Unexamined Patent Publication No. 2000-292589

In this way, power plants are required to improve power generation efficiency, and various measures have been taken to reduce waste heat. However, as described above, in the current circulation type boiler, the current situation is that the exhaust heat cannot be sufficiently utilized by discharging the drum water.

Therefore, the present invention provides a thermal power plant capable of further improving efficiency by utilizing waste heat, and a method for recovering waste heat.

The thermal power plant according to one aspect of the present invention includes a steam turbine driven by steam, a condenser that introduces exhaust steam from the steam turbine and condenses the exhaust steam into a condensed fluid, and the condenser. A circulating boiler that evaporates the condensed fluid from the water exchanger and introduces it into the steam turbine, a blow pipe that discharges a part of the condensed fluid from the circulating boiler, and the condensed fluid from the blow pipe. A circulating boiler system having a heat exchanger that exchanges heat between a certain discharged fluid and a fuel to recover the heat to the fuel, and an exhaust is introduced into the circulating boiler, and the exhaust and the circulation are introduced. It includes a gas turbine that exchanges heat with the steamer and burns the fuel after heat recovery in the heat exchanger.

In such a thermal power generation plant, the thermal energy of the discharged fluid discharged from the circulating boiler through the blow pipe can be recovered as the fuel of the gas turbine without being discarded to the outside of the system. Then, the fuel can be introduced into the combustor in a state where the fuel of the gas turbine is preheated by the thermal energy of the discharged fluid discharged through the blow pipe. Therefore, the thermal efficiency of the entire plant can be improved.

Further, in the above-mentioned thermal power generation plant, a cooling tower that circulates fluid between the condenser and the condenser, condenses the exhaust steam with the condenser, and generates condensed fluid from the exhaust steam, and the heat exchange. A cooling tower introduction pipe for introducing the discharged fluid after heat exchange with the condenser to the cooling tower may be further provided.

The discharged fluid discharged through the blow pipe can be introduced into the cooling tower after heat exchange in the heat exchanger. Therefore, the discharged fluid containing impurities is not introduced into the circulating boiler. Therefore, the water quality of the circulating boiler can be maintained in a clean state. In addition, since the discharged fluid discharged through the blow pipe is not discharged to the outside of the system while the temperature is high, it is not necessary to install equipment for reducing the temperature of the discharged fluid discharged through the blow pipe or processing equipment, and the system It is possible to reduce the manufacturing cost and the environmental load.

Further, in the above-mentioned thermal power generation plant, a high-pressure boiler, a medium-pressure boiler, and a low-pressure boiler that evaporate the condensed fluid from the water condensing device in parallel with each other as the circulation type boiler, and the high-pressure boiler as the blow pipe. The heat exchanger includes a high-pressure blow pipe provided in the medium pressure boiler, a medium pressure blow pipe provided in the medium pressure boiler, and a low pressure blow pipe provided in the low pressure boiler, and the heat exchanger is located on the upstream side of the fuel flow. It has a low temperature stage, a medium temperature stage, and a high temperature stage toward the downstream side, and the discharge fluid from the low pressure blow pipe is introduced into the low temperature stage, and the medium pressure stage is introduced from the medium pressure blow pipe. The discharged fluid from the high pressure blow pipe may be introduced into the high temperature stage.

The temperature of the discharged fluid from each boiler is different. Since each stage of the heat exchanger is provided according to the temperature level of the discharged fluid, the fuel can be efficiently heated step by step by using the thermal energy of the discharged fluid.

Further, in the above-mentioned thermal power generation plant, a high-pressure boiler, a medium-pressure boiler, and a low-pressure boiler that evaporate the condensed fluid from the water condenser in parallel with each other as the circulation type boiler, and the high-pressure boiler as the blow pipe. The high-pressure blow pipe provided in the medium-pressure boiler, the medium-pressure blow pipe provided in the medium-pressure boiler, and the low-pressure blow pipe provided in the low-pressure boiler. The fuel may be heat-recovered by the exhaust fluid from the pressure blow pipe.

With such a configuration, the thermal energy of the fluid discharged from the low temperature (low enthalpy) low pressure blow pipe is not recovered by the fuel, and the relatively high temperature (high enthalpy) high pressure blow pipe and Only the thermal energy of the fluid discharged from the medium pressure blow pipe is recovered in the fuel. Therefore, the fuel can be efficiently preheated.

Further, the exhaust heat recovery method according to one aspect of the present invention includes a steam turbine driven by steam and a condenser that introduces exhaust steam from the steam turbine and condenses the exhaust steam into a condensed fluid. , The condensed fluid from the condenser is evaporated and introduced into the steam turbine, and the exhaust is introduced into the circulating boiler, and heat is exchanged between the exhaust and the circulating boiler. A method for recovering exhaust heat in a thermal power plant including a gas turbine and a blow pipe for discharging a part of the condensed fluid from the circulating boiler, wherein the condensed fluid from the blow pipe is recovered. It includes an exhaust heat recovery step in which heat is exchanged between the discharged fluid and the fuel of the gas turbine so that the fuel recovers heat.

According to such a configuration, the thermal energy of the exhaust fluid discharged from the circulation type boiler through the blow pipe can be recovered as the fuel of the gas turbine without being discarded to the outside of the system. Then, the fuel can be introduced into the turbine in a state where the fuel of the gas turbine is preheated by the thermal energy of the discharged fluid discharged through the blow pipe. Therefore, the thermal efficiency of the entire plant can be improved.

Further, in the above-mentioned waste heat recovery method, the thermal power generation plant circulates a fluid with the condenser, and the condenser condenses the exhaust steam to generate a condensed fluid from the exhaust steam. A cooling tower may be further provided, and a fluid recovery step of introducing the discharged fluid into the cooling tower after heat recovery by the fuel in the waste heat recovery step may be further included.

The discharged fluid discharged through the blow pipe can be introduced into the cooling tower after heat exchange. Therefore, the discharged fluid containing impurities is not introduced into the circulating boiler. Therefore, the water quality of the circulating boiler can be maintained in a clean state. In addition, since the discharged fluid discharged through the blow pipe is not discharged to the outside of the system while the temperature is high, it is not necessary to install equipment for reducing the temperature of the discharged fluid discharged through the blow pipe or processing equipment, and the system It is possible to reduce the manufacturing cost and the environmental load.

According to the above-mentioned thermal power plant and waste heat recovery method, it is possible to further improve efficiency by utilizing waste heat.

It is an overall block diagram of the thermal power plant of 1st Embodiment of this invention. It is an overall block diagram of the thermal power plant of the 2nd Embodiment of this invention. It is an overall block diagram of the thermal power plant of the 3rd Embodiment of this invention. It is an overall block diagram of the thermal power plant which concerns on the 1st modification of the 3rd Embodiment of this invention. It is an overall block diagram of the thermal power plant which concerns on the 2nd modification of the 3rd Embodiment of this invention. It is an overall block diagram of the thermal power plant which concerns on 4th Embodiment of this invention. It is an overall block diagram of the thermal power plant which concerns on the modification of the 4th Embodiment of this invention.

[First Embodiment]
Hereinafter, the thermal power plant 1 of the first embodiment of the present invention will be described.
As shown in FIG. 1, the thermal power plant 1 includes a steam turbine 10, a condenser 11, a cooling tower 12, a circulation boiler 13 for introducing steam S into the steam turbine 10, and a circulation boiler 13 driven by steam S. It is provided with a circulation type boiler system 2 having a blow pipe 14 connected to, a heat exchanger 20 connected to the blow pipe 14, and a cooling tower introduction pipe 15 connecting the heat exchanger 20 and the cooling tower 12. .. Further, the thermal power plant 1 includes a gas turbine 21 that introduces an exhaust gas EG into the circulating boiler 13.

Although detailed illustration is omitted, the gas turbine 21 has a compressor 22, a combustor 23, and a turbine 24, and is burned by the combustor 23 together with the fuel F and the compressed air CA generated by the compressor 22, and has a high temperature. The turbine 24 is driven by introducing a high-pressure gas into the turbine 24. As a result, the generator 100 is rotated to generate electricity.

The combustor 23 is provided with a heater 26 that preheats the fuel F to be introduced into the combustor 23.
The compressor 22 is provided with an air cooler 27 for cooling the extracted air A. After the extracted air A is cooled by the air cooler 27, it is introduced into the turbine 24 to cool high-temperature parts and the like. The air cooler 27 does not necessarily have to be provided.
The turbine 24 is provided with a diffuser (not shown). Exhaust gas EG is discharged from this diffuser.

The steam turbine 10 is driven by steam S and generates electricity by rotating a generator 101.

The condenser 11 is connected to the steam turbine 10 and condenses the steam (exhaust steam) S from the steam turbine 10 into water W.

The cooling tower 12 is connected to the condenser 11 to circulate water (fluid) W with the condenser 11, condenses the steam S in the condenser 11, and is separated from the steam S by the condenser 11. Generate water W.

The circulation type boiler 13 is a so-called natural circulation type or forced circulation type boiler, and has a boiler main body 31 and an evaporator 32 connected to the boiler main body 31. The circulation type boiler 13 of this embodiment is a drum type boiler.
The boiler main body 31 stores water (condensed fluid) W and steam S. Further, the boiler main body 31 and the steam turbine 10 are connected by a steam introduction pipe 34, and the steam S in the boiler main body 31 can be introduced into the steam turbine 10.

The evaporator 32 is connected to the turbine 24, exchanges heat between the exhaust gas EG from the turbine 24 and the water W of the boiler main body 31, heats the water W and returns it to the boiler main body 31 as steam S.

Here, in the present embodiment, as the circulation type boiler 13, a high pressure boiler 13H, a medium pressure boiler 13I, and a low pressure boiler 13L that evaporate the water W from the condenser 11 in parallel with each other are provided. The exhaust gas EG of the gas turbine 21 is introduced into the evaporator 32 of each boiler 13 in the order of the high pressure boiler 13H, the medium pressure boiler 13I, and the low pressure boiler 13L. That is, the exhaust gas EG circulates in series with the evaporator 32 of each boiler 13.

An exhaust gas pipe 35 is connected to the evaporator 32 in the low-pressure boiler 13L. In the present embodiment, the exhaust gas pipe 35 is bifurcated downstream of the evaporator 32 and connected to the heater 26 and the air cooler 27. As a result, the exhaust gas EG that has passed through the evaporator 32 is used for preheating the fuel F in the heater 26 and preheating the air A extracted from the compressor 22. The exhaust gas EG is discharged to the outside of the system after preheating the fuel F and the air A.

The boiler main body 31 and the condenser 11 in each boiler 13 are connected by a boiler pipe 36. The boiler pipe 36 is branched into three branches on the way and is connected to the boiler main body 31 in each boiler 13. As a result, the water W from the condenser 11 is introduced in parallel to the boiler main body 31 in each boiler 13.

The blow pipe 14 is connected to the boiler main body 31 in each boiler 13 and discharges a part of the water W in the boiler main body 31 as drainage (drainage fluid) EW. In the present embodiment, as the blow pipe 14, a high pressure blow pipe 14H provided in the high pressure boiler 13H, a medium pressure blow pipe 14I provided in the medium pressure boiler 13I, and a low pressure blow pipe 14L provided in the low pressure boiler 13L are provided. Has been done. Further, each blow pipe 14 in each boiler 13 is connected by a merging pipe 17, and the drainage EW from each blow pipe 14 is collectively sent to the downstream side.

The heat exchanger 20 is connected to the merging pipe 17 and can introduce the drainage EW from each blow pipe 14. Further, the heat exchanger 20 is connected to a heat exchange pipe 37 that branches from an intermediate position between the condenser 11 and the boiler main body 31 in the boiler pipe 36. As a result, the water W heading from the condenser 11 to the circulating boiler 13 can be introduced into the heat exchanger 20. Then, the heat exchanger 20 exchanges heat between the drainage EW from each blow pipe 14 and the water W from the water recovery device 11 to recover the heat to the water W and heat the water W (exhaust heat recovery). Step), cool the drainage EW. The water W after heat exchange in the heat exchanger 20 is introduced into the boiler main body 31 in the high pressure boiler 13H through the preheated water pipe 38 connecting the heat exchanger 20 and the high pressure boiler 13H.

The cooling tower introduction pipe 15 connects the cooling tower 12 and the heat exchanger 20. The drainage EW after heat exchange in the heat exchanger 20 is introduced into the cooling tower 12 through the cooling tower introduction pipe 15 (fluid recovery step).

In the thermal power generation plant 1 described above, even if a part of the water W must be discharged as the drainage EW from the circulation type boiler 13 through the blow pipe 14 due to the standard or operational restrictions, the thermal energy of the wastewater EW is used. It can be recovered to the water W heading from the condenser 11 to the circulating boiler 13 by the heat exchanger 20 without being thrown out of the system. Then, the water W from the condenser 11 can be preheated by the heat energy of the drainage EW discharged through the blow pipe 14 and introduced into the high pressure boiler 13H.

Therefore, it is possible to improve the thermal efficiency of the entire circulation type boiler system 2, and it is possible to further improve the power generation efficiency in the thermal power generation plant 1 by utilizing the waste heat.

Here, the level of water quality required for the water W in the cooling tower 12 may be lower than the level of water quality generally required for the water W in the circulating boiler 13. In the present embodiment, the drainage EW discharged through the blow pipe 14 is introduced into the cooling tower 12 after heat exchange in the heat exchanger 20 without returning to the circulation type boiler 13, so that the drainage EW is discharged to the outside of the system. It can be used effectively without doing anything. Then, the water quality of the water W in the circulating boiler 13 can be maintained in a clean state.

Further, since the wastewater EW discharged through the blow pipe 14 is not discharged to the outside of the system while the temperature is high, the influence of heat on the equipment outside the system can be reduced. Therefore, it is no longer necessary to install equipment for cooling the wastewater EW discharged through the blow pipe 14 and equipment for treating the wastewater EW, and it is possible to reduce the manufacturing cost of the circulation type boiler system 2 and the environmental load. Become.

In the present embodiment, the water W after the heat exchange in the heat exchanger 20 is introduced into the high pressure boiler 13H, but the present invention is not limited to this. For example, it may be introduced into the medium pressure boiler 13I or the low pressure boiler 13L depending on the temperature and pressure of the water W after heat exchange.

Further, the exhaust gas EG after passing through the evaporator 32 does not have to be introduced into the heater 26 and the air cooler 27.

Further, in the present embodiment, the water W is heated by the evaporator 32 by the heat of the exhaust gas EG of the gas turbine 21, but for example, the water W may be heated by the evaporator 32 by another heat source. That is, in this case, the circulation type boiler system 2 of the present embodiment may be applied to a heat source other than the gas turbine 21. Specifically, the circulation type boiler system 2 of the present embodiment may be applied to a coal-fired conventional power plant or the like.

[Second Embodiment]
Next, the thermal power plant 1A of the second embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.
As shown in FIG. 2, the thermal power plant 1A differs from the first embodiment in that the circulation type boiler system 2A further includes a flash tank 40 provided at an intermediate position of the merging pipe 17. ..

The flash tank 40 is provided in the merging pipe 17 between the boiler main body 31 and the heat exchanger 20. The flash tank 40 reduces the temperature and pressure of the drainage EW from the blow pipe 14. Further, the flash tank 40 introduces the drainage EW from the blow pipe 14 connected to the boiler main body 31 of each boiler 13 to separate the drainage EW into the gas phase G and the liquid phase L. Then, the liquid phase L is introduced into the heat exchanger 20, and the gas phase G is introduced into the boiler main body 31 in the medium pressure boiler 13I and the low pressure boiler 13L through the gas phase introduction pipe 45. The introduction point of the gas phase G can be appropriately changed according to the state of the gas phase G.

In the thermal power plant 1A of the present embodiment described above, the wastewater EW discharged through the blow pipe 14 is flushed by the flash tank 40 to reduce the temperature (about 100 ° C.) and the pressure. As a result, it is possible to prevent backflow when the wastewater EW is introduced into the cooling tower. Further, after removing impurities in the flash tank 40, the gas phase G of the drainage EW can be returned to the circulation type boiler 13. Therefore, by discharging through the blow pipe 14, the supply amount of make-up water required when the amount of water W in the circulation type boiler 13 decreases can be reduced. Therefore, the cost of make-up water can be reduced.

[Third Embodiment]
Next, the thermal power plant 1B according to the third embodiment of the present invention will be described. The same components as those of the first embodiment and the second embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.
As shown in FIG. 3, the thermal power plant 1B is first implemented in that the circulation type boiler system 2B is provided with the heat exchanger 50 instead of the heat exchanger 20 and is not provided with the cooling tower 12. It is different from the embodiment and the second embodiment.

The heat exchanger 50 is connected to each blow pipe 14 by a merging pipe 17. As a result, the drainage EW from each blow pipe 14 is collectively introduced into the heat exchanger 50. Further, the fuel F of the gas turbine 21 is introduced into the heat exchanger 50. Then, heat exchange is performed between the waste water EW and the fuel F, the waste water EW is cooled, and the fuel F is made to recover heat to heat the fuel F (exhaust heat recovery step). The wastewater EW cooled by the heat exchanger 50 is discharged to the outside of the system.

Further, the heat exchanger 50 and the heater 26 are connected by a fuel introduction pipe 55. Through the fuel introduction pipe 55, the fuel F heated by the heat exchanger 50 is introduced into the heater 26 and further heated.

In the thermal power generation plant 1B of the present embodiment described above, the heat energy of the wastewater EW discharged from each boiler 13 through each blow pipe 14 is not wasted to the outside of the system, and the fuel of the gas turbine 21 is fueled by the heat exchanger 50. It can be collected in F. Then, the fuel F can be introduced into the combustor 23 through the heater 26 in a state where the fuel F of the gas turbine 21 is preheated by the thermal energy of the wastewater EW discharged through the blow pipe 14. Therefore, the thermal efficiency of the entire plant can be improved.

Further, the drainage EW from the blow pipe 14 is discharged to the outside of the system after being cooled by the heat exchanger 50, but the temperature of the drainage EW is relatively low. Therefore, even if the wastewater EW is discharged to the outside of the system, the equipment for lowering the temperature of the wastewater EW is not required, and the manufacturing cost of the system can be reduced and the environmental load can be reduced.

Here, as shown in FIG. 4, in the present embodiment, even if the heat exchanger 60 has a low temperature stage 61, a medium temperature stage 62, and a high temperature stage 63 from the upstream side to the downstream side of the flow of the fuel F. good. In the example of FIG. 4, the merging pipe 17 is not provided, and the low pressure blow pipe 14L is directly connected to the low temperature stage 61, and the drainage EW from the low pressure blow pipe 14L is introduced. Further, the medium pressure blow pipe 14I is directly connected to the medium temperature stage 62, and the drainage EW from the medium pressure blow pipe 14I is introduced. The high-pressure blow pipe 14H is directly connected to the high-temperature stage 63, and the drainage EW from the high-pressure blow pipe 14H is introduced.

The temperatures of the drainage EWs from the boiler main body 31 in each boiler 13 are different from each other. In the example of FIG. 4, since each stage of the heat exchanger 60 is provided according to the temperature level of the wastewater EW, the fuel F can be heated stepwisely and efficiently using the heat energy of the wastewater EW.

Further, as shown in FIG. 5, in the present embodiment, the merging pipe 17 may connect the high pressure blow pipe 14H and the medium pressure blow pipe 14I and may not be connected to the low pressure blow pipe 14L. In this case, the drainage EW from the high-pressure blow pipe 14H and the medium-pressure blow pipe 14I is collectively introduced into the heat exchanger 50 to heat the fuel F. The drainage EW from the low pressure blow pipe 14L is discharged to the outside of the system.

In the example of FIG. 5, the thermal energy of the wastewater EW from the low-pressure blow pipe 14L having a relatively low temperature (low enthalpy) is not recovered by the fuel F, and the high-pressure blow pipe 14H having a relatively high temperature (high enthalpy) is not recovered. And only the thermal energy of the wastewater EW from the medium pressure blow pipe 14I is recovered in the fuel F. Therefore, the fuel F can be efficiently preheated. It should be noted that only the thermal energy of the wastewater EW from the high-pressure blow pipe 14H may be recovered in the fuel F.

[Fourth Embodiment]
Next, the thermal power plant 1C according to the fourth embodiment of the present invention will be described. The same components as those in the first to third embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.
As shown in FIG. 6, the thermal power plant 1C is different from the third embodiment in that the circulation type boiler system 2C further includes a cooling tower 12 and a cooling tower introduction pipe 15.

The cooling tower introduction pipe 15 connects the cooling tower 12 and the heat exchanger 50. The drainage EW cooled by exchanging heat with the fuel F in the heat exchanger 50 is introduced into the cooling tower 12 through the cooling tower introduction pipe 15 (fluid recovery step).

In the thermal power generation plant 1C of the present embodiment described above, the wastewater EW discharged through the blow pipe 14 is introduced into the cooling tower 12 after heat exchange in the heat exchanger 50 without returning to the circulation type boiler 13. The wastewater EW can be effectively used without being discharged to the outside of the system, and the water W quality of the water W in the circulation type boiler 13 can be maintained in a clean state.

Here, as shown in FIG. 7, in this embodiment as in the example of the third embodiment shown in FIG. 4, the heat exchanger 60 has a low temperature stage 61, a medium temperature stage 62, and a high temperature stage 63. May be.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations thereof in each embodiment are examples, and the configurations may be added or omitted within a range not deviating from the gist of the present invention. , Replacements, and other changes are possible. Further, the present invention is not limited to the embodiments, but only to the scope of claims.

For example, in each of the above-described embodiments, three circulating boilers 13 are provided, but the number of circulating boilers 13 is not limited to three, and may be one or two, or four or more. There may be.

Further, instead of the steam turbine 10, a low boiling point medium Rankine cycle having a low boiling point medium turbine in which a low boiling point medium having a boiling point lower than that of water W is used as a working fluid may be applied to the above-described embodiment. .. Here, as a low boiling point medium, for example, the following substances are known.
・ Organic halogen compounds such as trichloroethylene, tetrachloroethylene, monochlorobenzene, dichlorobenzene and perfluorodecalin ・ Alkanes such as butane, propane, pentane, hexane, heptane, octane and decane ・ Cyclic alkanes such as cyclopentane and cyclohexane ・ Thiophen, ketone, Aromatic compounds ・ Refrigerants such as R134a and R245fa ・ Combinations of the above In this case, the low boiling point medium is also used for the fluid circulating between the cooling tower 12 and the water condensing device 11.

Further, the capacities of the heat exchangers 20, 50 and 60 may be designed according to the temperature of the water W returned to the cooling tower 12.
If the amount of heat exchanged in the heat exchangers 20, 50, 60 becomes too large, a bypass line may be provided to adjust the flow rate of the wastewater EW introduced into the heat exchangers 20, 50, 60. good.

1, 1A, 1B, 1C ... Thermal power plant 2, 2A, 2B, 2C ... Circulation type boiler system 10 ... Steam turbine 11 ... Water exchanger 12 ... Cooling tower 13 ... Circulation type boiler 13H ... High pressure boiler 13I ... Medium pressure boiler 13L ... Low pressure boiler 14 ... Blow pipe 14H ... High pressure blow pipe 14I ... Medium pressure blow pipe 14L ... Low pressure blow pipe 15 ... Cooling tower introduction pipe 17 ... Combined pipe 20 ... Heat exchanger 21 ... Gas turbine 22 ... Compressor 23 ... Combustion Vessel 24 ... Turbine 26 ... Heater 27 ... Air cooler 31 ... Boiler body 32 ... Evaporator 34 ... Steam introduction pipe 35 ... Exhaust gas pipe 36 ... Boiler pipe 37 ... Heat exchange pipe 38 ... Preheated water pipe 40 ... Flash tank 45 ... Boiler introduction pipe 50 ... Heat exchanger 55 ... Fuel introduction pipe 60 ... Heat exchanger 61 ... Low temperature stage 62 ... Medium temperature stage 63 ... High temperature stage 100 ... Generator 101 ... Generator S ... Steam W ... Water EW ... Drainage EG ... Exhaust gas F ... Fuel CA ... Compressed air A ... Air G ... Gas phase L ... Liquid phase

Claims (6)

A steam turbine driven by steam,
A condenser that introduces the exhaust steam from the steam turbine and condenses the exhaust steam into a condensed fluid.
A circulating boiler that evaporates the condensed fluid from the condenser and introduces it into the steam turbine.
A blow pipe that discharges a part of the condensed fluid from the circulating boiler,
A heat exchanger that exchanges heat between the exhaust fluid, which is the condensed fluid from the blow pipe, and the fuel, and causes the fuel to recover heat.
With a circulating boiler system,
A gas turbine that introduces an exhaust into the circulating boiler, exchanges heat between the exhaust and the circulating boiler, and burns the fuel after heat recovery in the heat exchanger.
A thermal power plant equipped with. A cooling tower that circulates a fluid with the condenser and condenses the exhaust steam with the condenser to generate a condensed fluid from the exhaust steam.
The thermal power generation plant according to claim 1, further comprising a cooling tower introduction pipe for introducing the exhaust fluid after heat exchange by the heat exchanger into the cooling tower. As the circulating boiler, a high-pressure boiler, a medium-pressure boiler, and a low-pressure boiler that evaporate the condensed fluid from the condenser in parallel with each other.
The blow pipes include a high-pressure blow pipe provided in the high-pressure boiler, a medium-pressure blow pipe provided in the medium-pressure boiler, and a low-pressure blow pipe provided in the low-pressure boiler.
Equipped with
The heat exchanger has a low temperature stage, a medium temperature stage, and a high temperature stage from the upstream side to the downstream side of the fuel flow.
The exhaust fluid from the low pressure blow pipe is introduced into the low temperature stage.
The exhaust fluid from the medium pressure blow pipe is introduced into the medium temperature stage.
The thermal power plant according to claim 1 or 2, wherein the discharged fluid from the high-pressure blow pipe is introduced into the high-temperature stage. As the circulating boiler, a high-pressure boiler, a medium-pressure boiler, and a low-pressure boiler that evaporate the condensed fluid from the condenser in parallel with each other.
The blow pipes include a high-pressure blow pipe provided in the high-pressure boiler, a medium-pressure blow pipe provided in the medium-pressure boiler, and a low-pressure blow pipe provided in the low-pressure boiler.
Equipped with
The thermal power plant according to claim 1, wherein the heat exchanger is used to recover heat to the fuel by the exhaust fluid from the high-pressure blow pipe and the medium-pressure blow pipe. A steam turbine driven by steam, a condenser that introduces exhaust steam from the steam turbine and condenses the exhaust steam into a condensed fluid, and a condenser that evaporates the condensed fluid from the condenser are used to evaporate the condensed fluid. A circulating boiler to be introduced into a steam turbine, a gas turbine in which exhaust is introduced into the circulating boiler and heat is exchanged between the exhaust and the circulating boiler, and one of the condensed fluids from the circulating boiler. It is a waste heat recovery method that recovers waste heat in a thermal power plant equipped with a blow pipe that discharges parts.
A method for recovering waste heat, which comprises a waste heat recovery step of performing heat exchange between the discharged fluid, which is the condensed fluid from the blow pipe, and the fuel of the gas turbine, and causing the fuel to recover heat. The thermal power plant further comprises a cooling tower that circulates a fluid to and from the condenser, condenses the exhaust steam with the condenser, and produces condensed fluid from the exhaust steam.
The waste heat recovery method according to claim 5, further comprising a fluid recovery step of introducing the waste fluid after heat recovery into the fuel in the waste heat recovery step into the cooling tower.

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